Stirring Rice

Many packages of rice instruct you "add to boiling weter and stir once". Why? What will happen to my rice if I do? Or do they mean literally stir only one revolution, rather don't repeatedly lift the lid in order to stir?

As to what happens if you stir it repeatedly while it cooks, the consistency gets sticky and gloppy for the same reasons that, done properly and with the right kind of rice, you can make risotto. But when you only do it a few times with ordinary long-grain and insufficient liquid, it just produces bad rice. ;)